The field of disclosure relates generally to a low sputtering, cross-field, gas switch and, more particularly, to a cross-field gas switch that reduces sputtering on a conduction surface of a cathode by reducing the kinetic energy of charged particles striking the conduction surface.
Cross-field gas switches, such as planar cross-field gas switches, are known. Conventionally, these switches include an electrode assembly, such as a cathode spaced apart from an anode, enclosed by a gas-tight chamber. The gas-tight chamber is filled with an ionizable gas, and a voltage is transiently applied to a control grid disposed between the anode and cathode to initiate a plasma path therebetween. The switch is operable, in the presence of an input voltage applied to the anode, to conduct a large electrical current between the anode and the cathode. The plasma path may be terminated by reverse biasing the control grid, such that the electrical current flowing from the anode to the cathode is transiently drawn off by the control grid (and accompanying circuitry), so that the gas between the control grid and anode can once again become insulating. Thus, the device functions as a gas filled switch, or “gas switch” in the presence of an input voltage and a conducting plasma.
Drawbacks associated with at least some known switches include heavy sputtering of cathode material during conduction. Specifically, many common gas switches experience a voltage drop of several hundred volts in the gap between the anode and the cathode. Typically, the large majority of this voltage drop (e.g., a “fall voltage”) is experienced at or near a conduction surface of the cathode (e.g., within a “fall distance” of the conduction surface), resulting, in most cases, in thermal losses and “sputtering” of the cathode conduction surface by incident charged particles (positive ions) that gain energy from the fall voltage. Sputtering tends to reduce the useful life of the gas switch, such as, for example, to a matter of hours or days in a conduction mode. Thus, conventional gas switches tend not to be feasible for large-scale, long-term, implementation in power systems where reliability, cost, and lifecycle are important considerations.